Spintronics

Thermoelectrics

Nanostructure & Self-Assembly   

Bio-Imaging

Quantum Dots -- Nanospintronic Study

The world of technology is moving rapidly from the realm of the electron to that of the quantum. Electron spin is one such quantum effect that has created a new science called spintronics. This emerging technology started attracting massive interest with the discovery of giant magnetoresistance (GMR) in the 1980s, which has already been adopted as the norm in the hard disk drive (HDD) manufacturing industry. Indeed, the impact of spintronics in the HDD industry is a mere indication of things to come. Spin-based devices have a vast number of potential applications, most notably in nonvolatile memory devices, magnetic sensors, and spin-based transistors. Magnetic sensors have already found a wide market application, thereby establishing the commercial viability of spin-based devices.

The idea to use the spin as an additional degree of freedom in electronics has recently received strong support from experiments showing unusually long spin dephasing times in semiconductors, the injection of spin-polarized currents into semiconductor material, ultrafast coherence spin manipulation and phase-coherent spin transport over distances of up to 100 mm. It is also well known that particles of solid materials whose dimensions are on the order of a few nanometers (i.e. quantum dots, QDs) exhibit electronic, optical and magnetic properties very different from the bulk material. The potential spintronic applications have opened over dozens of areas not only in conventional devices but also in quantum confined structures such as QDs. QDs are structures where charge carries are confined in all three spatial dimensions. For semiconductor QDs, the size region we are usually interested is between a few nm and 40 nm. Actually, a wide variety of optoelectronic QD devices has already been investigated and spectacular progress has been made in the field of QD laser and QD infrared detector devices, due to many advantages such as lower threshold current density, high gain, and high quantum efficiency. Among these QD-based devices, the quantum spin computing (QC) is one of the most ambitious spintronic devices and has drawn growing attention in recent years because it can deliver significant speed-up over classical computers due to inherent superposition and entanglement of a quantum system. In this proposed work, we will focus our effort on the preparation of some semiconductor QDs inspired by QC.

The objective of this project is to explore the further development of high-quality diluted magnetic semiconductor quantum dots (DMS QDs) as ideal materials for application in spin electronics (spintronics) with a particular use for quantum computing. The idea of using the electron spin of an atom as an additional degree of freedom in microelectronics materials related to information storage devices is feasible, and has received strong support from experiments. Such a spintronic effect may lead to a revolution in the next generation of electronic devices for memory storage and quantum computing. Our work focuses on (1) the preparation and the manipulation of various DMS QDs (mainly for III-V Group elements) with size-control and (2) the development of systematic analytical methods to characterize the spin behavior and the collective properties of these novel QDs for possible use in quantum computing design.  State of the art quantum computing designs are theoretically based on DMS QDs by trapping a spin of one (or a few) electron(s) inside a dimension-restricted, isolated semiconductor unit.

Present challenges → Can one synthesize high-quality InAs, InSb QDs?

                               → Can one synthesize high-quality GaAs QDs?

Link to talk of "spintronics":    high bandwidth WeCam    medium bandwidth WebCam

Link to Introduction: Introduction and Funding

Our Publications                                                             1st-y highlight

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Last Modified: 09/18/2008